         minus-sqrt (/ (- minus-b (Math/sqrt discriminant)) (* 2 a))]
     (max add-sqrt minus-sqrt)))
 
-;; We can calculate the time but we want the final position and
+;; We can now calculate the time to impact but we want the final position and
 ;; velocity. For position we can use the same function that we
 ;; rearranged above to derive the time.
 

;; us two results. In general we can say that we are interested in the
;; result with the maxium value.
;;
;; In this function you can see an example of call out to Java.
;; Clojure doesn't have an inbuilt sqrt function so we are calling out
;; to the java version. A function named in the form `foo/bar` means
;; it will call the function `bar` in the namespace `foo`. **NEED TO WRITE: WHAT IS A NAMESPACE?**

(defn time-to-canvas [position velocity acceleration]
  (let [a acceleration

  (+ (* acceleration time) initial-velocity))


;; These functions we just implemented can be joined up so that, given
;; an initial position and velocity we can return the final position and
;; velocity. This function doesn't explicitly ask for the acceleration
;; acting on the paint, it assumes only gravity is acting using the
;; constant defined earlier on.

(defn project-point [position velocity]
